Method and apparatus for natural biochemical decomposition of latrine

ABSTRACT

Method and apparatus for effecting the natural simultaneous biochemical decomposition of feces and urine involving the decomposition of the feces and the urine independently of each other and at different temperature but within a single apparatus. The urine is directed alone to an absorbent mineral pad and permitted to decompose as it passes slowly therethrough. The feces are mixed with a vegetable material and introduced into a separate decomposition area to a first stage where the temperature is maintained at 30*c, thereafter to a second stage where the temperature is maintained at 50* to 70*c. and thereafter to a third or final maturing stage where decomposition is completed. Excess air is introduced to the feces decomposition area during the decomposition and the feces mixture is maintained at a moisture level of 60% to 70% throughout the process, the decomposed urine being utilized to maintain the moisture level. The apparatus includes the principal chamber having at least a pair of canted planar members arranged in different planes but in a sequence, mineral wool members being carried by each of said members, said members being positioned to receive the urine and permit same to flow slowly, sequentially therethrough. The mats may be impregnated with nitrogen bacteria to aid decomposition. The feces are mixed with vegetable matter and introduced into the principal chamber, the floor of which being sloped in stages, the greater slope being at the first stage for initially receiving the mixture, the next stage being of lesser slope and the last stage being sloped in an opposite direction whereby totally defining a bowl-like configuration. The temperature within and the flow of air through the chamber is controlled.

United States Patent [191 Hellqvist Nov. 11, 1975 1 METHOD AND APPARATUS FOR NATURAL BIOCHEMICAL DECOMPOSITION OF LATRINE [75] Inventor: Ake O. W. Hellqvist, Djurhamn,

Sweden [73] Assignee: AB Sundsvalls Specialprodukter,

Sundsvall, Sweden [22] Filed: May 23, 1974 [21] Appl. No.: 472,634

[52] US. Cl. 4/120; 4/DIG. 12; 4/1 1 1;

4/1 16; 23/2591 [51] Int. CI. A47K ll/02; COSF 3/04 [58] Field of Search 4/1 1 1, l0, DIG. 12, 120,

Primary E.\aminerI-1enry K. Artis Attorney, Agent, or Firm Si1verman & Cass, Ltd.

[57] ABSTRACT Method and apparatus for effecting the natural simultaneous biochemical decomposition of feces and urine involving the decomposition of the feces and the urine independently of each other and at different temperature but within a single apparatus. The urine is directed alone to an absorbent mineral pad and permitted to decompose as it passes slowly therethrough. The feces are mixed with a vegetable material and introduced into a separate decomposition area to a first stage where the temperature is maintained at 30c, thereafter to a second stage where the temperature is maintained at 50 to 70C. and thereafter to a third or final maturing stage where decomposition is completed. Excess air is introduced to the feces decomposition area during the decomposition and the feces mixture is maintained at a moisture level of 60% to 70% throughout the process, the decomposed urine being utilized to maintain the moisture level. The apparatus includes the principal chamber having at least a pair of canted planar members arranged in different planes but in a sequence, mineral wool members being carried by each of said members, said members being positioned to receive the urine and permit same to flow slowly, sequentially therethrough. The mats may be impregnated with nitrogen bacteria to aid decomposition. The feces are mixed with vegetable matter and introduced into the principal chamber, the floor of which being sloped in stages, the greater slope being at the first stage for initially receiving the mixture, the next stage being of lesser slope and the last stage being sloped in an opposite direction whereby totally defining a bowl-like configuration. The temperature within and the flow of air through the chamber is controlled.

11 Claims, 1 Drawing Figure METHOD AND APPARATUS FOR NATURAL BIOCHEMICAL DECOMPOSITION OF LATRINE The present invention refers to a method and an apparatus for decomposing latrine in natural biochemical way. The invention is particularly suitable for toilets, but it is to be understood that the principles for the method and the apparatus may also be utilized in large compost plants for latrine and vegetable organic substances.

The classic method of handling latrine is that latrine containing feces, urine, paper etc. is dumped or spread in the nature without biochemical decomposition. This is unsanitary and the non-decomposed latrine contains large amounts of nitrogen and bacteria which has to be transformed or decomposed before the latrine may be made use of in the nature.

An apparatus has previously been proposed in which the latrine is collected in a large container in which the latrine is collected between layers of any vegetable organic substance and in which the piled material is allowed to stay until the latrine is almost completely decomposed and has taken a character which is suitable for earth enriching. The said previously proposed apparatus gives a very good result, but the method and the apparatus are disadvantageous in some respects.

The latrine comprises a mixture of feces and urine which mixture contains large amounts of nitrogen. In order to decompose the latrine bacterially it should be foreseen that the latrine obtains a suitable relationship between carbon and nitrogen and for the biochemical decomposition of latrine it is necessary to add carbon substrates such as by adding vegetable organic substance. The urine contains an essentially larger amount of nitrogen than the feces and the urine forms an essentially larger part of the latrine than the feces, some times as large as 80 to 90 larger. Therefore the latrine will contain a remarkable large amount of nitrogen and for the biochemical decomposition of the said nitrogen a large addition of organic vegetable substance is necessary. A plant for decomposing urine therefore must be of large dimensions and in spite of a rich addition of organic vegetable substance, the decomposition takes place rather slowly.

It is also known that the most suitable temperature for decomposing urine is +4 C while the most suitable temperature for decomposing feces is +28 to 30 C. Further the urine has some resterilizing action which to arrest on the decomposition process.

The basis for the present invention therefore is the intention to provide a decomposition of the urine in a urine compost and a decomposition of the feces in a feces compost, whereby the urine compost and the feces compost are kept completely independent of each other at least during the largest part of the decomposition process. It has shown that the urine may to some extent provide a decomposition of its own if it is stored some time, and by making use of this decomposition of its own it is possible to substantially reduce the addition of carbon substrate. Since the feces are free from urine, a relatively small amount of carbon substrate is necessary for the decomposition of the feces. By utilizing the principles of the present invention and by utilizing the different optimum temperatures for the feces decomposition and for the urine decomposition respectively it is possible to provide a more complete and quicker decomposition of feces and urine than 2 what is possible with biochemical decomposition of latrine and thanks to the reduced amount of carbon substrate required, the dimensions of the decomposition plant may be substantially reduced compared with a known plant available for biochemical decomposition of latrine.

According to the invention the process is carried through so that urine and feces are directed to respective decomposition plants arranged parallel one relative to the other and without mixing same, they are decomposed independently of each other.

The object of the process is to remove oxygen consuming material, to remove material which decays when being sedimented, to remove colloidally dissolved biochemically oxygen consuming substances called. BS-substances and to reduce the amount of harmful bacteria. The invention is based on the observation that a decomposition of the urine may be accomplished without any addition of material from outside, viz. if the urine is distribuuted over a large surface and is allowed to stay there so long that a nitro bacteria (nitrobact) layer is built up which layer contains nitrogen consuming bacteria. When executing the method the urine is brought todistribute itself in an inactive material having a large surface, whereupon during the slow movement of the urine through the said material, the urine is decomposed by nitrogen consuming bacteria which are formed and reformed so that the urine leaving said inactive materialis substantially decomposed and only contains precipitated mineral salts etc. The ideal temperature for building up the nitrobact layer is about +4 C. The temperature in the inactive material is maintained as close as possible to said ideal temperature. Suitable inactive material may include a mat of mineral wool or similar. .The compactness, the length of the mat and the inclination of the mat in relation to the horizontal plane is determinative of the time required for the urine to pass through the perforate mat, i.e. the time during which nitrobact are allowed to be formed and re-formed and thereby during which the nitrobacts are allowed to decompose the nitrogen and other constituents of the urine. In order to reduce the magnitude of the decomposition plant, it may be formed to enable the urine to pass through several mats provided in zigzag form before it leaves the plant. In order to start the urine decomposition process it may be suitable to add nitrogen consuming bacteria and in such case the mat of mineral wool or similar material may be impregnated with such bacteria before being installed. I

As mentioned above, the decomposition of the feces takes place independently of the decomposition of urine, and for the decomposition of the feces, an addition of a carbon substrate is needed. Such carbon substrate may for instance be ground bark from coniferous trees or leaf trees but it is also possible to use vegetary slops etc. in order to obtain the adequate relationship between carbon and nitrogen in the feces mixture. In order to obtain a quick and good decomposition of the feces mixture, a temperature of about 30 C or more is necessary. The temperature during the very decomposition process preferably should not be more than 45-70 C, since in such case the evaporation of liquid will be very high and there will be a risk for drying of the feces mixture. The ideal carbon-nitrogen relationship for the decomposition is considered to be about 33 parts of carbon for l, 5 parts of nitrogen, but the relationship may be changed within fairly wide ranges. The

decomposition of feces may be accomplished by an an aerobic or an aerobic process. The anaerobic process I process in aerobic way. For this purpose, an addition of air in excess is needed. The decomposition of the feces product is accomplished by mixing the carbon substrate like ground bark or putting same into layers with the feces on a feces bed where the feces mixture during the decomposition is brought to slowly move downwards. During the complete process a suitable temperature is kept. For starting the process it may be necessary to add a substantial amount of heat depending on the ambient temperature circumstances but after the process has started it goes ahead exothermically and to enable the addition of heat to be reduced or even cease.

The decomposition of the feces may take place in several different steps, for instance in three steps ac cording to the following:

In step 1 there is basically a decomposition of the mixture of feces and carbon substrate by a transformation of nitrogen and organic substance. The decomposition takes place at a temperature of at least 35 C. Due to the exothermic reaction of the process, the temperature may sometimes become as high as 70 C. Gen erally this does not involve any disadvantages but there is an increased evaporation and a greater amount of liquid (water) than otherwise has to be added. A high temperature gives an increased bacterial action, and from this point of view the high temperature may be preferred. In order to effect a suitable decomposition, the percentage of moisture ought to be about 60-75 If the moisture percentage becomes lower than that percentage, water has to be added from outside.

ln'step 2 there is a continued decomposition of the mixture of feces and carbon substrate, but in this step the temperature maintained is at 5070 C so that there is a pasteurizing and a killing of harmful bacteria.

Step 3 is an after-maturing step in which the mixture of carbon substrate and decomposed feces is allowed to be stationary for about three months. The temperature during this after-maturing step is not critical and the temperature may be allowed to fall to 30 C.

Both in step 2 and step 3 the percentage of moisture ought to be maintained and if the feces product tends to dry, liquid has to be added from outside.

The heat for the process may be applied in different ways, but suitably heat slings are mounted at the bottom of the apparatus in which the decomposition takes place. Alternatively, the heat may be added by heating the air which is necessary for the aerobic process before the air is blown over the feces mixture.

In the accompanying single FIGURE of the drawing diagrammatically illustrates an embodiment of an ap paratus particularly adapted for executing the method according to the invention. Generally the apparatus comprises a decomposition or compost container 1 which is mounted under the floor 2 of a house. The container 1 has a collar 3 projecting through the floor which is provided with a toilet chair 4 or similar. The lower part of the decomposition container 1 is provided with a feces decomposition bed 5, which slopes downwards from the point where feces and carbon substrate are supplied to a place close to the opposite end of the container, i.e. the front, where the bottom or floor level rises somewhat. In the illustrated embodiment, the bottom or floor is formed by three planar steps or stages corresponding to the above described three steps'of the decomposition. Above the feces decomposition bed 5, there is a urine decomposition bed 9 comprising two planes or shelves 10 and 11 provided at an angle to each other. The shelves form an angle of about lO-20" with the horizontal plane and each carries a mat 12 and 13 respectively formed of mineral wool or any other inert material having a large surface. Depending on how long the urine is desired to be kept in the mats 12 and 13 of mineral wool the number of angularly mounted shelves or planes l0 and 11 may be changed either by increasing or decreasing said number. The

angle formed by the planes 10 and 11 relative to the horizontal plane may be changed. Likewise the compactness of the mineral wool mat may be varied. For transferring the urine from the toilet chair 4 to the first one 12 of the two mineral wool mats there is a collection channel 14 at the front end of the toilet chair. In front of the collection channel 14 a rotatable disc 14a may be mounted which can take two positions, viz. one position shown in full lines in the drawing and another position shown with dotted lines. The disc 14a may be adjusted by means of a handle or a pedal in any suitable way. The urine descending through the collection channel 14 is absorbed in the first mineral wool mat 12 and slowly flows through said mat, and during this time nitrogen bacteria (nitrobacts) are formed. and reformed; these bacteria consuming the nitrogen of the urine. After having passed the first mineral wool mat 12 the urine flows down on the second mineral wool mat 13 and then passes through mat 13 in the same manner as it passes through the mat 12.

One or more valves are provided at the lower edge of the toilet chair for letting in air. The relatively cool air enteringthe apparatus flows downwards as indicated with the arrows 16 and leaves through an air outlet 17 at the rearward edge of the toilet chair 4. Air may also both ends which mainly extends along the said bottom or some part thereof as indicated in the drawing.

In order to obtain the different temperatures of stage 6 and stage 7 they may be formed with electric heat slings and the said heat slings may be thermostat regulated in order to keep a correct temperature.

In order to make it possible to introduce the mineral wook mats l2 and 13 or by demand to substitute same and to empty the decomposition container from decomposed feces, doors 18 are provided at the front end of the container.

The decomposed urine leaving the urine decomposition bed 9 may be drained through a tube 19 extending through the feces bed 5 or in an alternative embodi ment of the invention, the decomposed urine may be distributed over the decomposed feces mixture by means of a perforated tube 20 or similar. By this the percentage of moisture may be kept in the feces mix ture during the above described after-maturing thereof.

The above described apparatus is only anillustrating example of the invention and it is obvious to the man skilled in the art that a number of alternative solutions may be presented within the scope of the appended claims.

What I claim is:

1. Apparatus for effecting the simultaneous decomposition of feces and urine comprising a decomposition container having a toilet chair mounted at the upper part thereof, said decomposition container containing a feces decomposition bed, a urine decomposition bed said beds being as separate units, and means directing the urine primarily to the urine decomposition bed and said urine decomposition bed being offset from the feces decomposition bed.

2. Apparatus according to claim 1 in which the feces.

decomposition bed has a vaulted bottom floor said floor being steeply sloped at the location where the feces are received, the inclination being successively decreased toward the opposite end of the container to terminate in a portion having a slope in the opposite direction so as to define a bowl-formation.

3. Apparatus according to claim 2, in which the feces decomposition bed has three planar stages having different angles relative to a horizontal plane.

4. Apparatus according to claim 2 in which the feces decomposition bed is formed with means therein establishing a predetermined minimum temperature at least at the end where the feces is received.

5. Apparatus according to claim 1 in which said urine decomposition bed has at least one sloping planar member provided with a filter seated thereupon and having a large surface and which is positioned to receive the urine, whereby to permit the same to flow slowly therethrough thereby providing a biochemical decomposition of the urine.

6. Apparatus according to claim 5 in which said apparatus has at least two filters provided successively after. each other and through which the urine is brought to flow by turn during the decomposition thereof.

7. Apparatus according to claim 5 in which the filters comprise a porous mass formed of an inert material.

8. Apparatus according to claim 6 in which the filters comprise mats formed of mineral wool.

9. Apparatus according to claim 5 in which the filters contain an inoculated culture of nitrogen bacteria.

10. Apparatus according to claim 5 and means coupled to the urine decomposition bed for receiving and spreading the biochemically decomposed urine over the feces decomposition bed.

11. Apparatus according to claim 1 and means are provided for supplying excess air to the feces decomposition bed. 

1. Apparatus for effecting the simultaneous decomposition of feces and urine comprising a decomposition container having a toilet chair mounted at the upper part thereof, said decomposition container containing a feces decomposition bed, a urine decomposition bed said beds being as separate units, and means directing the urine primarily to the urine decomposition bed and said urine decomposition bed being offset from the feces decomposition bed.
 2. Apparatus according to claim 1 in which the feces decomposition bed has a vaulted bottom floor said floor being steeply sloped at the location where the feces are received, the inclination being successively decreased toward the opposite end of the container to terminate in a portion having a slope in the opposite direction so as to define a bowl-formation.
 3. Apparatus according to claim 2, in which the feces decomposition bed has three planar stages having different angles relative to a horizontal plane.
 4. Apparatus according to claim 2 in which the feces decomposition bed is formed with means therein establishing a predetermined minimum temperature at least at the end where the feces is received.
 5. Apparatus according to claim 1 in which said urine decomposition bed has at least one sloping planar member provided with a filter seated thereupon and having a large surface and which is positioned to receive the urine, whereby to permit the same to flow slowly therethrough thereby providing a biochemical decomposition of the urine.
 6. Apparatus according to claim 5 in which said apparatus has at least two filters provided successively after each other and through which the urine is brought to flow by turn during the decomposition thereof.
 7. Apparatus according to claim 5 in which the filters comprise a porous mass formed of an inert material.
 8. Apparatus according to claim 6 in which the filters comprise mats formed of mineral wool.
 9. Apparatus according to claim 5 in which the filters contain an inoculated culture of nitrogen bacteria.
 10. Apparatus according to claim 5 and means coupled to the urine decomposition bed for receiving and spreading the biochemically decomposed urine over the feces decomposition bed.
 11. Apparatus according to claim 1 and means are provided for supplying excess air to the feces decomposition bed. 